1Mix flour, sugar, baking soda, and cocoa till well blended. Add the salad dressing or mayonnaise, cold water, and vanilla till mixture is smooth. Pour into a greased and floured 9x13 cake pan. Bake at 350 degrees for 30 minutes or till a toothpick inserted in the middle of the cake comes out clean. Frost with your choice of frosting. Enjoy!